LibC: Fix bug in scanf() family where we'd capture invalid data.

LibC/scanf.cpp

@@ -33,8 +33,6 @@
 #include <string.h>
 #include <ctype.h>
 
-#define MAXLN 512
-
 static const char* determine_base(const char* p, int& base)
 {
  if (p[0] == '0') {
@@ -119,54 +117,13 @@ int atob(unsigned int* vp, const char* p, int base)
  return 0;
 }
 
-static int vfscanf(FILE*, const char*, va_list);
-static int vsscanf(const char*, const char*, va_list);
-
 #define ISSPACE " \t\n\r\f\v"
 
-int scanf(const char* fmt, ...)
-{
- int count;
- va_list ap;
-
- va_start(ap, fmt);
- count = vfscanf(stdin, fmt, ap);
- va_end(ap);
- return count;
-}
-
-int fscanf(FILE *fp, const char* fmt, ...)
-{
- va_list ap;
- va_start(ap, fmt);
- int count = vfscanf(fp, fmt, ap);
- va_end(ap);
- return count;
-}
-
-int sscanf(const char *buf, const char* fmt, ...)
-{
- va_list ap;
- va_start(ap, fmt);
- int count = vsscanf(buf, fmt, ap);
- va_end(ap);
- return count;
-}
-
-static int vfscanf(FILE *fp, const char* fmt, va_list ap)
-{
- char buf[MAXLN + 1];
- if (!fgets(buf, MAXLN, fp))
- return -1;
- int count = vsscanf(buf, fmt, ap);
- return count;
-}
-
-static int vsscanf(const char *buf, const char *s, va_list ap)
+int vsscanf(const char *buf, const char *s, va_list ap)
 {
  int base = 10;
  char *t;
- char tmp[MAXLN];
+ char tmp[BUFSIZ];
  bool noassign = false;
  int count = 0;
  int width = 0;
@@ -220,16 +177,25 @@ static int vsscanf(const char *buf, const char *s, va_list ap)
  else if (*s == 'b')
  base = 2;
  if (!width) {
- if (isspace(*(s + 1)) || *(s + 1) == 0)
+ if (isspace(*(s + 1)) || *(s + 1) == 0) {
  width = strcspn(buf, ISSPACE);
- else
- width = strchr(buf, *(s + 1)) - buf;
+ } else {
+ auto* p = strchr(buf, *(s+1));
+ if (p)
+ width = p - buf;
+ else {
+ noassign = true;
+ width = 0;
+ }
+ }
  }
  strncpy(tmp, buf, width);
  tmp[width] = '\0';
  buf += width;
- if (!noassign)
- atob(va_arg(ap, uint32_t*), tmp, base);
+ if (!noassign) {
+ if (!atob(va_arg(ap, uint32_t*), tmp, base))
+ noassign = true;
+ }
  }
  if (!noassign)
  ++count;

LibC/stdio.cpp

@@ -424,5 +424,41 @@ int remove(const char* pathname)
  return rmdir(pathname);
 }
 
+int scanf(const char* fmt, ...)
+{
+ va_list ap;
+ va_start(ap, fmt);
+ int count = vfscanf(stdin, fmt, ap);
+ va_end(ap);
+ return count;
+}
+
+int fscanf(FILE* stream, const char* fmt, ...)
+{
+ va_list ap;
+ va_start(ap, fmt);
+ int count = vfscanf(stream, fmt, ap);
+ va_end(ap);
+ return count;
+}
+
+int sscanf(const char* buffer, const char* fmt, ...)
+{
+ va_list ap;
+ va_start(ap, fmt);
+ int count = vsscanf(buffer, fmt, ap);
+ va_end(ap);
+ return count;
+}
+
+int vfscanf(FILE* stream, const char* fmt, va_list ap)
+{
+ char buffer[BUFSIZ];
+ if (!fgets(buffer, sizeof(buffer) - 1, stream))
+ return -1;
+ return vsscanf(buffer, fmt, ap);
+}
+
+
 }
 

LibC/stdio.h

@@ -78,6 +78,8 @@ void perror(const char*);
 int scanf(const char* fmt, ...);
 int sscanf (const char* str, const char* fmt, ...);
 int fscanf(FILE*, const char* fmt, ...);
+int vfscanf(FILE*, const char*, va_list);
+int vsscanf(const char*, const char*, va_list);
 int setvbuf(FILE*, char* buf, int mode, size_t);
 void setbuf(FILE*, char* buf);
 void setlinebuf(FILE*);